An approximate method for solving unsteady transitional and rarefied flow regimes in pulsed pressure chemical vapor deposition process using the quiet direct simulation method

Chin Wai Lim, Hadley M. Cave, Mark C. Jermy, Susan P. Krumdieck, Jong Shinn Wu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

The Quiet Direct Simulation (QDS) method is a kinetic-based flux scheme that computes true-direction fluxes of mass, momentum and energy with high computational efficiency. In QDS, the molecular velocity is represented by the Maxwell-Boltzmann equilibrium distribution approximated by a Gauss-Hermite quadrature. The QDS algorithm is suitable for parallelization with its highly local nature. In this paper, the QDS method is used to simulate highly unsteady low pressure flows encountered in a Pulsed Pressure Chemical Vapor Deposition (PP-CVD) reactor. Two simulations were conducted to study the PP-CVD reactor flow field at 1Pa and 1kPa reactor base pressures. The time required to establish the quasi-steady under-expanded jet is found to be ∼5ms, and the jet dissipates within 1ms of the end of injection. Simulation results also show uniform molecular arrival at the depositing substrate surface to promote uniform deposition. This important information is important to set up PP-CVD operating conditions as well as the reactor design. The assumption of the local Maxwell-Boltzmann equilibrium distribution used in the QDS scheme is then verified by examining the gradient length local Knudsen number based on the density, and by estimating the average number of particles collisions within each computational cell in one computational time step. The validity of local equilibrium assumption is found satisfactory at 1kPa reactor based pressure but not at 1Pa. However, the similarity of flow phenomena in both simulations suggests QDS to be a quick approximation method for low pressure flow simulations.

Original languageEnglish
Title of host publication27th International Symposium on Rarefied Gas Dynamics - 2010, RGD27
Pages1039-1044
Number of pages6
EditionPART 1
DOIs
Publication statusPublished - 18 Oct 2011
Event27th International Symposium on Rarefied Gas Dynamics, RGD27 - Pacific Grove, CA, United States
Duration: 10 Jul 201115 Jul 2011

Publication series

NameAIP Conference Proceedings
NumberPART 1
Volume1333
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other27th International Symposium on Rarefied Gas Dynamics, RGD27
CountryUnited States
CityPacific Grove, CA
Period10/07/1115/07/11

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Lim, C. W., Cave, H. M., Jermy, M. C., Krumdieck, S. P., & Wu, J. S. (2011). An approximate method for solving unsteady transitional and rarefied flow regimes in pulsed pressure chemical vapor deposition process using the quiet direct simulation method. In 27th International Symposium on Rarefied Gas Dynamics - 2010, RGD27 (PART 1 ed., pp. 1039-1044). (AIP Conference Proceedings; Vol. 1333, No. PART 1). https://doi.org/10.1063/1.3562782